Modification of uncertainty analysis in adapted material flow analysis: Case study of nitrogen flows in the Day-Nhue River Basin, Vietnam

•A modified uncertainty analysis procedure in material flow analysis is proposed.•A new and effective criterion is detected from the plausibility test.•Uncertainty of parameter is identified by a budget-based sensitivity analysis.•Reassessment procedure increases the plausibility of the model.•The u...

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Bibliographic Details
Published in:Resources, conservation and recycling conservation and recycling, 2014-07, Vol.88, p.67-75
Main Authors: Do, Nga Thu, Trinh, Duc Anh, Nishida, Kei
Format: Article
Language:English
Subjects:
Applied sciences
Budgeting
Computer simulation
Confidence intervals
Continental surface waters
Criteria
Exact sciences and technology
Freshwater
Groundwaters
Material flow analysis (MFA)
Mathematical analysis
Mathematical models
Monte Carlo simulation
Natural water pollution
Nutrient
Pollution
Reassessment procedure
River basins
Uncertainty
Water treatment and pollution
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Summary:•A modified uncertainty analysis procedure in material flow analysis is proposed.•A new and effective criterion is detected from the plausibility test.•Uncertainty of parameter is identified by a budget-based sensitivity analysis.•Reassessment procedure increases the plausibility of the model.•The uncertainty analysis controls the quality of environmental impact assessment. Nitrogen flows impacted by human activities in the Day-Nhue River Basin in northern Vietnam have been modeled using adapted material flow analysis (MFA). This study introduces a modified uncertainty analysis procedure and its importance in MFA. We generated a probability distribution using a Monte Carlo simulation, calculated the nitrogen budget for each process and then evaluated the plausibility under three different criterion sets. The third criterion, with one standard deviation of the budget value as the confidence interval and 68% as the confidence level, could be applied to effectively identify hidden uncertainties in the MFA system. Sensitivity analysis was conducted for revising parameters, followed by the reassessment of the model structure by revising equations or flow regime, if necessary. The number of processes that passed the plausibility test increased from five to nine after reassessment of model uncertainty with a greater model quality. The application of the uncertainty analysis approach to this case study revealed that the reassessment of equations in the aquaculture process largely changed the results for nitrogen flows to environments. The significant differences were identified as increased nitrogen load to the atmosphere and to soil/groundwater (17% and 41%, respectively), and a 58% decrease in nitrogen load to surface water. Thus, modified uncertainty analysis was considered to be an important screening system for ensuring quality of MFA modeling.
ISSN:0921-3449
1879-0658
DOI:10.1016/j.resconrec.2014.04.006